In the past, optical methods were usually used for chassis measurement; in these methods, special measurement adapters having optical identifiers or markings needed to be mounted on the respective vehicle wheel, and then evaluated using image technology. DE 197 57 760, for example, discloses corresponding methods. Because the installation of corresponding auxiliary equipment on the vehicle or the bodywork is time-consuming, further measurement methods have been developed that allow measurement without add-ons or modifications to the vehicle.
In EP 0 280 941, for example, laser lines are projected onto a wheel that is rotated locally in a roller set. The evaluation method carried out there for the measured values that are obtained explicitly requires that the wheel rotate only locally. A structured illumination in the form of dots or ribbons of light, and a subsequent evaluation of the image data obtained, are also explained in EP 1 505 367 and in DE 10 2006 048 725.
Conventional methods for axle measurement must, disadvantageously, use either features attached to the vehicle that are dynamically tracked via an image sequence. Artificially attached features must be laboriously attached to the vehicle by the particular service facility. The known image processing and evaluation methods furthermore often require that the wheel rotate only locally, and that, for example, the vehicle not move. In the case of the evaluation and sensing methods using a structure projection, a wheel rotation as a rule cannot be detected. Determination of a wheel rim runout is thus possible only with low accuracy, even when the vehicle is traveling past.
It is therefore desirable to make available an improved method for determining the axle or wheel geometry of a vehicle.